from The New York Times:
The Man Who Keeps the Wheels Turning at the U.S. Open

By CINDY SHMERLER SEPT. 11, 2017
Shingo Kunieda was fretting. It was Thursday, and Kunieda, his coach, his trainer, his clothing sponsor and his wife were all bent over, trying to pump air into the tires of his wheelchair.

In an hour, Kunieda, one of the most accomplished men’s wheelchair tennis players in the world, would be contesting the first wheelchair match at Arthur Ashe Stadium, and something was not right.

Nearby, Mike Zangari was operating a portable compression machine, one of two that he keeps in the trunk of his car. He had realized that a rubber tube inside the tire of Kunieda’s wheelchair had a slow leak. It would most likely affect his ability to maneuver around the court.
“Having a broken chair, for a wheelchair player, is like another athlete having a severe injury,” said Dan James, the former national manager of wheelchair tennis for the United States Tennis Association. “They can’t play.”

To ensure that a wheelchair competitor’s equipment is functional, the U.S.T.A. hired Zangari, 57, a professional wheelchair salesman and technician in Glen Cove, N.Y. He has been on the job since 2004, the year wheelchair tennis began as an exhibition event at the United States Open. It became a full tournament the next year.
Zangari, who was born with spina bifida, uses a wheelchair too. He has played wheelchair tennis, basketball and softball and currently teaches basketball to able-bodied preschoolers and kindergartners.
Zangari travels with a toolbox filled with nuts, bolts and screws, and extra tubing, casters and even glass cleaner that can act as a lubricant to help stuck wheels turn.

During matches, Zangari is positioned near the court.

“Wheelchairs are both personal and customized,” Zangari said. “These athletes know exactly what they need and want. They know their seat angle and how high their back rest should be.”

Chairs typically cost from $3,000 to $6,000, depending on whether they are made of aluminum or titanium. The best players, like Kunieda and the American David Wagner, have sponsorship deals that cover the cost.
Tennis wheelchairs are different not only from those used in everyday life but also from those used in other sports. They have two large, inverted wheels that players use for speed and quick turns of direction. They also have three small wheels — two in front, one in back — and a wheelie, or anti-tip bar, that prevents the chair from tumbling over as players race around the court.

Wheelchair tennis allows for two bounces of the ball, but all other rules are the same as in the conventional game. At tournaments like the U.S. Open, athletes compete in singles, doubles and quads, an event for quadriplegics in which they can tape their racket to their hands.

Should a player’s equipment malfunction in the middle of a match, Zangari, or the player, has 20 minutes to fix the chair or the player must default. Major International Tennis Federation tournaments are required to have a wheelchair technician on site.
Unlike able-bodied professionals, who fill their on-court bags with several additional rackets, a couple of extra outfits and maybe a pair of sneakers, top international wheelchair competitors travel with extra wheels, tires, spokes, casters and tubing.

“Our chairs are our shoes, but they’re not shoes,” said Wagner, 43, a two-time U.S. Open quad singles champion and seven-time doubles winner. “We have to take very good care of our equipment. But with all the travel we do, most of the damage to our chairs is done by the airlines.”

As soon as players arrive at the Open, they meet with Zangari to ensure all equipment is in good working order. A tire with even a tiny decrease in pressure can hinder a player’s ability to retrieve a drop shot. Some players can fix their own problems; others can’t.
“Usually, players do preventative maintenance every day,” Zangari said. “They rotate their tires, just like a car, because of the high-pitch angle and so they don’t get worn out and can last longer.”

Once, at a tournament in Boca Raton, Fla., Wagner said, he was dashing back for a shot when his front wheel got caught on a grate, which shattered the wheel’s caster.

“Fortunately, I carry all of my own equipment,” said Wagner, the top seed in the Open’s quad wheelchair division. “I can change a tire in five minutes.”
But for those who can’t, Zangari is a lifesaver.

“I don’t think the word ‘lifesaver’ can even describe how valuable he is,” said Joanne Wallen, the U.S.T.A.’s director of wheelchair tennis and the U.S. Open wheelchair tournament director. “There is only one person we would trust to do this job, and it’s Mike.”

Kunieda, 33, who has won 20 major singles championships, is known for not allowing others to touch his equipment. But he did allow Zangari to tinker with his chair, removing the wheels and then replacing the tubing and tires before his first match.

Racing against the clock, Zangari completed his assignment just in time for Kunieda’s prematch warm-up, sweat dripping down his face.

“These competitors are so precise and so are their chairs,” Zangari said, trying to mask his stress level. “If there’s anything off — tire pressure, ball bearings, wheels — they know. They’ll see it right away. It’s my job to make sure that doesn’t happen.”